Viologen-templated bromoplumbate: a new in situ synthetic method and energy gap engineering

Changing N -substituents to modify energy gaps is important for the diverse applications (photochromism, photocatalysis, etc. ) of viologen-based compounds. In situ N -substitution using alcohols under solvothermal and acidic conditions is an effective and common synthetic method for viologen-templated metal halides. In this work, we found that replacing alcohols with alkenes could reduce the reaction temperature dramatically to room temperature. A new cis / trans -viologen-templated bromoplumbate with a novel 1-D chain structure built by edge-sharing planar [Pb 3 Br 9 ] 3− oligomers was successfully obtained. This bromoplumbate hybrid has a narrower energy gap compared with bulk PbBr 2 , which has been well explained by linear optical response spectra calculations and PDOS analysis.